The Economics of Nanosilicon in Solar Panel Recycling
At present, solar energy accounts for more than 2% of the world’s total energy production, and this percentage is continuously increasing. However, in order for solar energy to continue being an environmentally sustainable option, measures must be taken to address the harmful disposal process that currently exists. You may find my article on this topic informative here. It is worth noting that by 2070, the amount of waste generated from photovoltaic (PV) technology may reach the same level as the PV materials in use.
A solution to this problem could be economically incentivising solar panel recycling using a process that converts the waste PV silicon into nanosilicon for retail. But does this make sense economically? Well, let’s look at the numbers.
Trashing a solar panel is easy and cheap.
For consumers with residential solar panels, this is as easy as putting the panels with the rest of their garbage. For corporations, solar panels must be sent to waste management centers. This would have a labour cost and center fees which usually end up costing cents per solar panel.
Recycling a solar panel is a lot harder.
Currently, it is difficult for an individual to recycle their residential solar panel. There simply aren’t many facilities. In fact, I spent time researching where I could recycle solar panels locally — to no avail. The closest I could find was e-waste disposal centers. These aren’t uncommon, but these facilities aren’t legit recycling centers. These places just remove the aluminum/wiring and trash the rest of the solar panel. Some solar panel retailers do offer recycling programs, so returning to where they were bought can be a way to recycle solar panels. This is really it.
It’s also expensive.
For consumers, the cost is to get the solar panels to a recycling facility.
For corporations who don’t recycle, the cost is also transportation to a recycling facility, plus a recycling fee.
For corporations who recycle, the costs come from proprietary shredding machines and leaching drums, as well as the energy costs (specifically with removing the glass with heat) and labour.
The cost difference between these two options gives an easy choice.
At the end of the day, it costs anywhere from <$1 to $3 USD to send a solar panel to a landfill. This is compared to $10 to $45 to recycle it. Only about $3 can be recovered by selling the aluminum, copper and glass. The current recycling process doesn’t sell the two most valuable materials in a solar panel — the silver and silicon. In fact, the silver and silicon make up only 4% of the mass of a solar panel but make up 58% of the value!
Scale this up to hundreds of thousands of solar panels, and recycling is all wasted money in the eyes of consumers and corporations.
The nanosilicon process has costs too.
The process is the same with the addition of some steps. The first is obtaining the silicon. This would be using KOH to essentially dissolve all materials of the solar cells. Potassium hydroxide is easily available and when bought in bulk, will cost just cents per solar panel. (This step would also remove the need for glass to be removed using heat) Next, the silicon will need to be purified (The silicon does not need to be solar-grade (6N) silicon, but 80% pure). This costs around 50 cents per gram, or around $33 USD per 60 cell solar panel (typical residential size). The actual purity of the silicon before purification doesn’t matter, since the process stays the same. The final cost for the process is running the silicon through a ball mill to break it down. A ball mill can cost anywhere from tens to hundreds of thousands of dollars.
The nanosilicon conversion process can flip this cost disparity.
Most of the few solar panel recycling organizations estimate that they need about 1–3 thousand tons of solar panels to be recycled every year to stay in business. On the lower end, this is 50 000 solar panels.
For the sake of numbers, let’s imagine a facility that recycles 10 000 solar panels a year.
For simplicity, let’s assume the solar panels were delivered to their doorstep.
The facility is spending about $35 per solar panel to get it ready for the ball mill.
The facility would be spending $100 000 / 10 000 = $10 per solar panel to make up for the cost of a ball mill within a year.
The rest of the traditional recycling process can add anywhere from $15 to $45 to this process. Let’s average this at $30. This comes to a total of $75 spent per solar panel to obtain nanosilicon. In theory, this nanosilicon is worth $36 000 per kg of silicon which, considering material loss during purification and etching, can be found in 100 solar panels. This is about 10 000 / 100 = 100kg of nanosilicon, or $36 000 * 100 = $3.6M. Of course, there are many other factors that can affect this number, but none that can significantly affect if this process would turn a profit or not. $3.6M / 10 000 gives $360 revenue per solar panel. $360 — $75 = $285 of profit per solar panel. This does not include transportation costs to obtain the solar panels, sell the nanosilicon, labour, etc. These costs would not add up to losing another $285 — the point is, this process can turn a profit.
PV recycling can become the norm!
At the end of the day, the reason people don’t recycle solar panels is the cost. Even other reasons like the lack of mass adoption are caused because the recycling process is too expensive. If people had the option to recycle solar panels at the same cost, or even cheaper than to trash them, they would have all the reason to do it! One hurdle is for residential solar panels, trashing them takes next to no effort. Everyone has access to a garbage bin, and recycling facilities can’t beat this convenience. Instead, offering things like money (even just a few dollars!) can be a good enough incentive for people to choose to recycle. It is entirely possible that we can have a world where the majority of solar panels are recycled!
In order for solar energy to be green, it must be fully green for its whole lifespan.
- By 2070, the mass of PV waste could actually be equal to the mass of PV in service!
- It costs anywhere from <$1 to $3 USD to send a solar panel to a landfill, versus $10 to $45 to recycle it.
- There is value in solar panels, that isn’t sold during the recycling process. It is in silver, copper and silicon.
- If the silicon can be converted to nanosilicon, it can economically incentivise recycling.
- In a simplified facility example, a solar panel can be recycled and the nanosilicon can be sold for expenses of around $75 USD.
- This can end up making $285 of profit per solar panel — of course probably reasonably less since it’s simplified.
- If solar panel recycling can be done for the same price, or even cheaper than trashing them, a world where solar panel recycling is the norm is achievable.
